I have been trying out spamgourmet and its very empowering.
However, one thing that I note is that if you use the feature for forwarding-on mail from one of your registered spamgourmet addresses, the mail headers still reveal the sender's domain and IP address etc.
I don't want this to sound like a complaint, and in fact it may have been the originator's wish to do this, since it ensures that the sender is still accountable or traceable to some extent. However, I think it needs to be pointed out, in case anyone thinks that their outgoing message is completely anonymous. In fact it isn't anonymous and being able to see the sender's domain name, could provide the persistent spammer with a means of directing mail to 'sales@' or 'administrator@' the user's domain.
Here's an example - note mydomain.com, which was my original hidden sending domain.
[...]
Received: from xxx.xxx.xxx.xxx.adsl.dynamic.myserv.net ([xxx.xxx.xxx.xxx] helo=[192.168.0.xxx])
by svr1.ab.myhost.co.uk with esmtpa (Exim 4.53)
id xxxxxxxxxxxx
for ; Mon, 14 Dec 2009 12:43:02 +0000
Message-ID: <4B2632C6.7080903@mydomain.com>
Date: Mon, 14 Dec 2009 12:42:46 +0000
From: xyz123.4.myaccount@spamgourmet.com
User-Agent: Thunderbird 2.0.0.18 (Windows/20081105)
[...]